Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Pompoen rassendemo voor verwerking : verkenning naar producteisen en geschiktheid voor teelt in Nederland
    Wijk, C.A.P. van - \ 2012
    Lelystad : PPO AGV (Biokennis rapport 469) - 27
    pompoenen - cucurbita - rassenproeven - rassen (planten) - kwaliteit voor industriële verwerking - vruchtgroenten - vollegrondsgroenten - marktverkenningen - nederland - vollegrondsteelt - pumpkins - cucurbita - variety trials - varieties - industrial processing quality - fruit vegetables - field vegetables - market surveys - netherlands - outdoor cropping
    In 2011 is een demoteelt met pompoenrassen voor verwerking aangelegd en op basis daarvan met de ketenpartijen een discussie gevoerd over de afzet van verwerkt product. Eerst zijn daarbij de afzetniches voor verwerking benoemd en daar zijn de eisen voor verwerking aan gekoppeld. Tegen deze achtergrond zijn de rassen in de demoteelt vervolgens bediscussieerd. Ook zijn van de rassen een aantal meetbare eigenschappen vastgelegd.
    Bewaarrot bij pompoen beperken
    Wijk, C.A.P. van - \ 2007
    Wageningen : Wageningen UR (Biokennis bericht : Akkerbouw & vollegrondsgroente ) - 2
    akkerbouw - cucurbita - bewaarziekten - gewasbescherming - fusarium - biologische landbouw - vollegrondsgroenten - arable farming - cucurbita - storage disorders - plant protection - fusarium - organic farming - field vegetables
    Vooral aan het eind van de bewaarperiode zijn veel pompoenen niet meer te verkopen door rot. Diverse schimmels zijn de oorzaak. Rot is te beperken door een zorgvuldige oogst en bewaring. Warmwaterbehandeling lijkt alleen te helpen bij rassen die minder bewaarbaar zijn. In deze publicatie de tips en adviezen naast elkaar.
    Lichtefficientie bij courgette : onderzoek naar plantverdeling, plantdichtheden en bladsnoei
    Janse, J. - \ 2000
    Naaldwijk : Proefstation voor Bloemisterij en Glasgroente, Vestiging Naaldwijk (Rapport / Proefstation voor Bloemisterij en Glasgroente 298) - 26
    cucurbita - cucurbita pepo - vruchtgroenten - licht - lichtrelaties - droge stof - ophoping van drogestof - plantdichtheid - plaatsen op afstand - assimilatie - plantenontwikkeling - cucurbita - cucurbita pepo - fruit vegetables - light - light relations - dry matter - dry matter accumulation - plant density - spacing - assimilation - plant development
    Onderzoek naar verhoging van de productie bij courgette door betere lichtefficiëntie en sturing van assimilaten naar de vruchten
    Gebruikswaarde van verschillende onderstammen voor courgette in verband met Fusarium : onderzoek 1999
    Janse, J. ; Elgersma, R. - \ 1999
    Naaldwijk : Proefstation voor Bloemisterij en Glasgroente, Vestiging Naaldwijk (Rapport / Proefstation voor Bloemisterij en Glasgroente 224) - 19
    cucurbita - courgettes - fusarium - plantenziekteverwekkende schimmels - cultivars - rassen (planten) - gebruikswaarde - economische impact - onderstammen - nederland - kwaliteit - cucurbita - marrows - fusarium - plant pathogenic fungi - cultivars - varieties - use value - economic impact - rootstocks - netherlands - quality
    Geintegreerde en biologische bestrijding van ziekten en plagen van peulvruchten
    Anonymous, - \ 1979
    Wageningen : Pudoc (Literatuurlijst / Centrum voor Landbouwpublikaties en Landbouwdocumentatie no. 4328)
    bibliografieën - biologische bestrijding - bestrijdingsmethoden - cucurbita - geïntegreerde bestrijding - geïntegreerde plagenbestrijding - plantenziekten - plantenplagen - gewasbescherming - pompoenen - bibliographies - biological control - control methods - cucurbita - integrated control - integrated pest management - plant diseases - plant pests - plant protection - pumpkins
    Overzicht van arbeid, materialen en opbrengsten van vroege en late stooktomaten, stookkomkommers, paprika's (onverwarmd) en meloenen (licht verwarmd) in Delft en het Westland
    Anonymous, - \ 1974
    Den Haag : [s.n.] (Overzicht / Landbouw-economisch instituut no. 626) - 17
    komkommers - cucumis melo - cucumis sativus - cucurbita - solanum lycopersicum - meloenen - pompoenen - statistiek - tomaten - nederland - zuid-holland - cucumbers - cucumis melo - cucumis sativus - cucurbita - solanum lycopersicum - melons - pumpkins - statistics - tomatoes - netherlands - zuid-holland
    Pseudoperonospora cubensis bij komkommer en andere cucurbitaceae
    Anonymous, - \ 1973
    Wageningen : [s.n.] (Literatuurlijst / Centrum voor landbouwpublikaties en landbouwdocumentatie no. 3519)
    bibliografieën - komkommers - cucumis melo - cucumis sativus - cucurbita - meloenen - plantenziekten - afwijkingen, planten - plantenziektekunde - plantenplagen - gewasbescherming - pompoenen - bibliographies - cucumbers - cucumis melo - cucumis sativus - cucurbita - melons - plant diseases - plant disorders - plant pathology - plant pests - plant protection - pumpkins
    Rhythms in stomatal opening of bean leaves = Ritmen in de opening van de huidmondjes bij de boon
    Hopmans, P.A.M. - \ 1971
    Wageningen University. Promotor(en): S.J. Wellensiek. - Wageningen : Veenman - 86
    cucurbita - pompoenen - transpiratie - evapotranspiratie - cucurbita - pumpkins - transpiration - evapotranspiration

    An analytical study of the cyclic stomatal behaviour in leaves of bean, Phaseolus vulgaris L. 'Vroege Wagenaar', was made in order to explore the cycling, to study different aspects of plant water relations and of the action mechanism of the stomata. A general method of investigation was recording of the difference of temperature of leaf and air with thermocouples in a constant environment.

    Introductory observations

    Plants grown at low light intensity showed a higher tendency to sustained cycling (higher instability of the stomatal apparatus) than those grown at higher light intensity. At the higher light intensity non-aeration of the nutrient solution increased the tendency to cycling with a more than additive effect. It is suggested that the lower capacity to take up water of non-aerated roots was involved in the higher tendency to cycling. Cycling over the whole plant was frequently disturbed by bringing cycling of a part of the active stomata out of phase. Cycling was induced by changing abruptly any factor that affected stomatal opening, by entrainment with cycling air vapour pressure, by entrainment with cycling plant water potential, and apparently spontaneously.

    Younger leaves showed shorter free-running periods than older ones. When both were attached on the same plant, cycling in the younger leaves entrained cycling in the older ones.

    Water relations of cycling

    Amplitudes of cycling increased by decreasing air humidity and by increasing the water potential in the root medium. A time delay in the adjustment of the turgor of the guard cells to the plant water potential is assigned to be the cause of overshooting of the active stomatal movement and as to be the factor amplifying both passive opening and closing movement. Cycling only occurred when an important resistance to water uptake was present in the transpiration stream. In intact plants this resistance was located in the roots. The water potential cycled in the whole plant down to this resistance, synchronizing cycling in the whole plant. During each cycle the root resistance increased during the sub-period with low rates of water uptake and decreased delayed at subsequently decreasing plant water potential. Due to the fact that the fall of root resistance was enhanced by increasing root temperature, both cycling of stomatal opening and cycling of root resistance were intensified.

    A diagrammatic conceptual model is presented, showing the pathway of the transpiration stream, of the transfer of water within the leaf, and of the stomatal control system of the water balance of the leaf. A negative feedback control circuit in it indicates how active stomatal movements function, while a positive feedback circuit shows how passive stomatal movements function during cycling.

    Circadian rhythm in steady and cycling stomatal openings

    In continuous light a circadian rhythm in non-cycling stomatal opening was found, which phase could be caused to shift. Cycling was most intense at the time that in similarly treated plants the maximum was attained in the circadian rhythm in the opening in non-cycling stomata and least intense half a circadian period later. In continuous darkness during the first day after the last photoperiod, stomata opened in a cyclic way with a daily pattern in the amplitudes as well as in the number of cycles. During photoperiods of 17 hours the noncycling stomatal opening in leaves, attached to plants with and without root systems, as well as in isolated leaves followed a daily pattern. During these photoperiods the modulation of amplitudes and periods showed the same daily pattern as during the circadian rhythm in continuous light. During the daily dark periods stomata remained closed. A daily pattern was observed in the onset of stomata] opening after short dark periods in the course of the daily photoperiod. The data suggest that one endogenous circadian oscillator, situated in the leaves, caused the circadian rhythm in non-cycling stomatal opening and modulated stomatal cycling in continuous light, continuous darkness and during the daily photoperiods.

    Environmental effects on cycling stomata

    The time between the onset of light and the beginning of stomatal opening increased with increasing length of the. preceding dark period at equal phases of the circadian rhythm. After 1 hour in the light the effect of the preceding dark period had almost disappeared. After removal of the trifoliates the periods in the primary leaves gradually shortened in the course of some days. It is suggested that this increased activity was caused by a reduced competition for minerals, enzymes and proenzymes from the root.

    Cycling was frequently damped by increasing the irradiation intensity. Irradiation intensity beyond 34,000 erg cm -2sec -1affected the rate of CO 2 exchange, but not the period or amplitude of sustained cycling. When the irradiation intensity on the lower surface of the leaf during the diurnal photoperiod was decreased from 2100 to 800 erg cm -2sec -1, cycling continued. The amplitude decreased and the period increased, mainly due to the increase of the sub-period with minimal stomatal opening. During the photoperiod 150 erg cm -2sec -1on the upper surface of the leaf induced overshooting stomatal opening. The sub-period with minimal stomatal opening, being similar to STÅLFELT'S 'Spannungsphase' (build-up period), increased at decreasing irradiation intensity due to an increase in time required for the guard cells to exceed the counterpressure from the surrounding cells, hence, the product rule of STÅLFELT applied here.

    The build-up period of stomatal opening increased by decreasing the CO 2 -concentration of the air from 300 to 200 to 0 ppm.

    Enhancing the temperature in light decreased the period. This effect was clearly distinguished from the effect of increasing vapour pressure gradient. The Q 10 of decrease fell gradually from approximately 4 between 17° and 20°C to approximately 1.5 between 25° and 29°C. The sub-period with minimal stomatal opening was mainly affected. In light the same effect of temperature on cycling was found in CO 2 -free air as in normal air and the same on cycling in detached leaves as in attached leaves. A temperature increase in darkness induced stomatal cycling; this was assigned for the major part to the stimulation of the active opening component. Temperature is concluded to exert an influence independent of the effect of CO 2 -concentration and of the water balance.

    The effects of light and temperature on cycling support the existing hypothesis for an active ATP using potassium pump as a mechanism for stomatal opening.

    Conclusive remarks

    Several internal plant factors play a part in causing instability of the stomatal apparatus, but also the habit of the plant. Cycling must be expected to occur in the field and in the glasshouse, especially at low air humidity, when these factors favour instability. Severe stomatal cycling is suggested to decrease mean assimilation rate.

    Phytochrome in seeds of some curcurbitaceae: in vivo spectrophotometry
    Malcoste, R. ; Boisard, J. ; Spruit, C.J.P. ; Rollin, P. - \ 1970
    Wageningen : Veenman (Mededelingen Landbouwhogeschool Wageningen 70-16) - 16
    cucurbita - pompoenen - fytochroom - plantenpigmenten - analyse - spectrofotometrie - wetenschap - natuurwetenschappen - cucurbita - pumpkins - phytochrome - plant pigments - analysis - spectrophotometry - science - natural sciences
    Studies on the nature of the incompatibility in a cucurbitaceous graft
    Stigter, H.C.M. de - \ 1956
    Wageningen University. Promotor(en): S.J. Wellensiek. - Wageningen : Veenman - 51
    cucurbitaceae - cucumis melo - meloenen - cucurbita - pompoenen - cucumis sativus - komkommers - plantenfysiologie - cucurbitaceae - cucumis melo - melons - cucurbita - pumpkins - cucumis sativus - cucumbers - plant physiology - cum laude
    Musk melon (M), cucumber (C) and Cucurbita ficifolia (F) could succesfully be grafted in all single combinations, except for M/F which required foliage on the stock to survive. Defoliation of this stock caused the plant to wilt and die, generally in 4-5 days; necrosis started in the stock: a rapid and specific collapse of its sieve tubes occurred before any visible symptom was evident in the melon scion. With stock foliage present, a good union between xylem and phloem of the partners was formed.

    Growth and other phenomena reacted strongly to the number of leaves on a stock. The effect of these leaves depended largely on light intensity. M/F plants could recover from advanced stages of incompatibility, by renewed contact with leaves of the stock species.

    From these and experiments with double grafting it was concluded that the stock leaves provided the stock with some specific substance (enzymic or hormonal) enabling the stock phloem to function normally.

    Shortage or complete absence of this substance might have influenced some enzymic process in the complex of sieve tube and companion cell, upsetting metabolism as shown by local accumulation of starch. The stock leaves depended on root vitality, which in turn was determined by interaction with the scion. The growth-regulating activity of the stock leaves thus proved to be connected with the nature of the interactions between M and F.

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